1. Field of the Invention
The present invention relates to a magnetic recording medium mounted on a magnetic recording and reproducing apparatus such as a hard disk drive, etc., and in particular, relates to a method of fabricating a magnetic recording medium capable of recording magnetic information with a high recording density and further reproducing the information with low noise.
2. Description of the Related Art
Increasing the capacity of a hard disk drive (HDD) that plays a central role in a magnetic recording and reproducing apparatus is needed with the advancement of the information society. Particularly, the recording density of the HDD is improving at breakneck speed such as an annual rate at or over 100%. In order to realize a high recording density, first, it is necessary to increase the recording density of the magnetic recording medium itself mounted in the HDD, although an improvement such as heightening of the sensitivity of the magnetic head is also needed.
Accordingly, further reducing noise of the magnetic recording medium is required in order to ensure a required S/N. Thus, in regard to a magnetic film being a data-recording layer of the magnetic recording medium, the main technical problems are to refine crystal grains of the magnetic film for recording data according to the miniaturization of bit cells and to isolate the crystal grains magnetically so that magnetic coupling between the crystal grains is reduced as much as possible.
Conventionally, against the problems, studies for coping with the problems such as the improvement of the composition of the magnetic film or adjusting sputter conditions have been performed.
However, a structure such that noise is reduced more certainly is needed in a magnetic film of a magnetic recording medium that enables to realize recording at high density over 100 GB/in From that point of view, as the ideal conditions for a magnetic recording medium are listed, it is necessary to satisfy the following 4 conditions:
that is,
(a) The sizes of the crystal grains are approximately 2 through 3 nm, and small;
(b) The dispersion in the sizes of the crystal grains is small;
(c) Furthermore, the filling factor of the crystal grains is fully high; and
(d) Then, each crystal grain isolates fully magnetically; including solving the aforementioned problems.
The adjustment of the composition of the magnetic film or the adjustment of the sputter conditions, which is an aforementioned conventional technique, is one of the effective methods in the techniques for facilitating the refinement or magnetic isolation of the crystal grains of the magnetic film.
However, in these methods, it is particularly difficult to suppress the product on of the dispersion in the sizes of the crystal grains so as to form crystal grains having a uniform diameter, and it is difficult to form a magnetic film that satisfies all of the 4 conditions.